The overall objective is to elucidate changes in the synthesis and phosphorylation of DNA-binding proteins during the onset of transformation in NRK cells transformed by a temperature-sensitive mutant of Rous sarcoma virus. Cells will be either prelabeled or pulse-labeled with radioisotopes during the course of transformation. DNA-binding proteins will be fractionated on columns of DNA-cellulose and analyzed by electrophoresis on SDS-polyacrylamide gels. Gels will be sliced transversely for scintillation counting and sliced longitudinally for gel autoradiography. The synthesis and functional significance of a 93,000 dalton DNA-binding polypeptide will be investigated.